These studies are directed to find out the control of granulosa cell maturation and luteinization in the rhesus monkey and pig. In the pig granulosa cells will be harvested from small follicles and cultured in the presence of FSH, insulin, thyroxin, cortisol and various stimulatory fractions of porcine follicular fluid isolated from large mature follicles. After various times in culture the number of LH receptors, ability to accumulate cyclic AMP and progesterone in response to LH and the ability to convert androsteredione to estrogen will be measured. These studies should give insight into normal intrafollicular control of granulosa cell receptor maturation. Since the normal fate of a follicle is to become atretic rather than develop some aspects of characterization of atretic porcine follicles will be evaluated and the existence of a possible follicular fluid atretogenic factor sought after. Since inhibin F (folliculostatin; FSH suppressing activity) has been observed in monkey follicular fluid and monkey ovarian vein blood further studies will be carried out in vivo and in vitro to see which cell type of the follicle makes it and how the secretion varies according to the stage of the menstrual cycle. Monkey ovarian vein will be cannulated prior to ovulation and the ovarian venous inhibin levels measured before and after granulosa and thecal removal from preovulatory follicle. Thecal and granulosa secretion of inhibin will also be measured in culture. Hormonal control of inhibin secretion by monkey granulosa cell cultures will also be investigated and correlated with follicular steroidogenesis. Monkey ovarian blood will be collected throughout the menstrual cycle and assayed for inhibin. It is possible that follicular inhibin may control FSH secretion which in turn plays a role in controlling follicular maturation. Changes in levels of monkey ovarian vein inhibin occurring before, during and after puberty will be examined to see if changes in ovarian secretion of inhibin play a possible role in initiation of puberty.